In internal combustion engines it is desirable to schedule various operational parameters of the engine as a function both of the engine speed and the engine load. Determination of engine speed or revolutions per minute (RPM) is well established for internal combustion engines. Prior digital systems determining the timing of engine spark ignition as a function of engine speed (RPM) are disclosed in U.S. Pat. Nos. 5,392,753 and 4,924,831.
However, to date, there has been no economical method of determining the load on a small internal combustion engine. The conventional methods of determining engine torque involve measuring strain or angular displacement of a segment of the crankshaft, a mounting element or an element of the drive train. These methods are not cost effective for small engine applications. Therefore. small engines have used fuel injection event and/or ignition timing that is either fixed or based on the engine speed.